This invention relates generally to toner image reproduction machines, and more particularly to such a machine including a high capacity feeder having a safe tiltable paper tray.
In a typical toner image reproduction machine, for example an electrostatographic printing process machine, a photoconductive member is charged to a substantially uniform potential so as to sensitize the surface thereof. The charged portion of the photoconductive member is exposed to a light image of an original document being reproduced. Exposure of the charged photoconductive member selectively dissipates the charges thereon in the irradiated areas. This records an electrostatic latent image on the photoconductive member corresponding to the informational areas contained within the original document.
After the electrostatic latent image is recorded on the photoconductive member, the latent image is developed by bringing a developer material into contact therewith. Generally, the developer material comprises toner particles adhering triboelectrically to carrier granules. The toner particles are attracted from the carrier granules to the latent image forming a toner powder image on the photoconductive member. The toner powder image is then transferred from the photoconductive member to a copy sheet. The toner particles are heated to permanently affix the powder image to the copy sheet.
The foregoing generally describes a typical black and white electrostatographic printing machine. With the advent of multicolor electrophotography, it is desirable to use an architecture which comprises a plurality of image forming stations. One example of the plural image forming station architecture utilizes an image-on-image (IOI) system in which the photoreceptive member is recharged, re-imaged and developed for each color separation. This charging, imaging, developing and recharging, re-imaging and developing, all followed by transfer to paper, is done in a single revolution of the photoreceptor in so-called single pass machines, while multi-pass architectures form each color separation with a single charge, image and develop, with separate transfer operations for each color.
In single pass color machines and other high-speed printers it is desirable to feed a wide variety of media for printing thereon. A large variety or latitude of sheet sizes and sheet weights, in addition to various coated and other specialty papers must be fed at high speed to the printer by sheet feeding apparatus that may involve tray tilting.
In the event of a system failure severe damage to the entire system is likely to occur unless the tray tilting drives are stopped.
In accordance with the present invention, there is provided a safe tiltable sheet feeding apparatus that includes a tiltable sheet support tray, having a lead edge and a trail edge, for supporting a stack of sheets to be fed lead edge first from the stack. The tiltable sheet feeding apparatus also includes a feed head adjacent the sheet support tray for feeding a top sheet of the stack from the stack and an elevator assembly for independently raising, lowering and tilting the trail edge of the sheet support tray. The elevator assembly includes elevator drive motors, a controller, side frames defining lead edge elevator slots, and trail edge elevator slots. Importantly, the tiltable sheet feeding apparatus includes an overtilt safety sensor device mounted within the trail edge elevator slots and connected to the controller, for sensing overtilt of the trail edge of the sheet support tray, and for preventing resulting damage to the tiltable sheet feeding apparatus